1. Field of the Invention
The present invention relates in general to a device for interconnecting copper and bolt pipes, of an air conditioner.
2. Description of the Prior Art
As shown in FIG. 1, a typical device for coupling the copper and bolt pipes of an air conditioner includes a bolt pipe 10, which is coupled to the outdoor unit (not shown) of the air conditioner and is provided with an outer-threaded part 12, and through which the fluid refrigerant flows. The coupling device also includes a copper pipe 20 with a flared part 21. The copper pipe 20 is coupled to the indoor unit (not shown) of the air conditioner and supplies the fluid refrigerant from the outdoor unit to the indoor unit. The above coupling device further includes a nut 30, which couples the copper pipe 20 to the bolt pipe 10 through a flared-type pipe joint. In the above flared-type pipe joint, one end of the nut 30 is tightly fitted over the flared part 21 of the copper pipe 20 while compressing the flared part 21 onto the end of the bolt pipe 10, thus preventing leakage of the fluid refrigerant from the coupled pipes 10 and 20. The other end of the nut 30 is screwed onto the outer-threaded part 12 of the bolt pipe 10.
As shown in FIGS. 1 and 2, the end surface of the bolt pipe 10 is inclined in order to form an inclined surface 11, which is brought into close contact with the flared part 21 of the copper pipe 20. The cylindrical end portion of the bolt pipe 10, which is spaced apart from the inclined surface 11, is externally threaded in order to form the outer-threaded part 12. The outer-threaded part 12 of the bolt pipe 10 is brought into engagement with the inner-threaded part 33 of the nut 30.
As shown in FIG. 1, the flared part 21 of the copper pipe 20, which comes into close contact with the inclined end surface 11 of the bolt pipe 10, is formed by bulging one end of the copper pipe 20 so that the flared part 21 is bent thereby forming the inclined surface corresponding to the inclined end surface 11 of the bolt pipe 10.
Meanwhile, the center of the nut 30 is axially bored in order to form an axial opening 31, through which the copper pipe 20 is tightly fitted into the nut 30 as shown in FIGS. 1 and 2. The upper section of the inner surface of the opening 31 is inclined in order to form an inclined shoulder 32, which is brought into contact with the outer surface of the flared part 21 of the copper pipe 20.
However, the above coupling device has the following problems. That is, the flared part 21 of the copper pipe 20 is formed by bulging the end of the pipe 20 so that the flared part 21 is bent. In addition, both the inclined end surface 11 of the bolt pipe 10 and the inclined shoulder 32 of the nut 30, which are brought into contact with the inner and outer surfaces of the flared part 21 respectively, are inclined in the same manner as the flared part 21. In this regard, the bent portion of the flared part 21 of the copper pipe 20 is hardened during the bulging process forming the flared part 21. Therefore, when the nut 30 has been tightened in order to couple the copper pipe 20 to the bolt pipe 10 for a lengthy period of time and is loosened in order to separate the copper pipe 20 from the bolt pipe 10, the bent portion of the hardened flared part 21 may be easily cracked or cut so that the copper pipe 20 must be replaced by a new one. Another problem of the above coupling device resides in that the bolt pipe 10 may be easily moved relative to the copper pipe 20 or be damaged thereby causing leakage of the fluid refrigerant from the junction around the flared part 21.